Question 13 Million-Year-Old Ant Fossil Discovered

13 Million-Year-Old Ant Fossil Discovered
By Olivia Ferrari
Published 25th of April, 2025
National Geographic


From the National Geographic News Article:

‘Now the oldest ant specimen known to science, the roughly half-inch-long 113-million-year-old impression preserved in limestone was found in northeastern Brazil, and is a new genus belonging to the “hell ant” subfamily Haidomyrmecinae. Hell ants only lived during the Cretaceous period, which ended 66 million years ago.’

‘The newly identified specimen was part of a collection of insect fossils from a fossil-rich stone quarry known as the Crato Formation, and housed at the University of São Paulo’s Zoology Museum. The research team used 3D imaging to view inside the well-preserved specimen and identify its spot on ants’ evolutionary tree.’

‘Hell ant fossils indicate early ants evolved sophisticated predatory strategies. Their bizarre jaws paired with a horn on their head were probably used to pin down or impale other insects before eating them, allowing them to capture relatively large prey.’

‘“It’s a very unusual kind of mandible that you can’t find in any [living] insect today,” says Lepeco. Scientists have speculated that hell ants could have used these mandibles to grab drops of water or nectar to transport to their nest and feed larvae, but using them to grab or impale insects is the more likely theory, thinks Lepeco.’

‘The new fossil is also the first evidence discovered of hell ants on Gondwana, the prehistoric Southern Hemisphere megacontinent.’

‘“From previous fossil records, we know that hell ants were successful and diverse, occurring in three continents over 20 million years,” says Sosiak, “so this new hell ant really reinforces this pattern, expanding their geographic and temporal diversity.”’

From the Current Biology Report:
Summary:
‘The so-called hell ants of the subfamily Haidomyrmecinae comprise a group of morphologically unique ants exclusive to the Cretaceous.4 They represent some of the earliest known ants in the fossil record, preserved as amber inclusions in deposits in France, Myanmar, and Canada.

Here, we report the oldest known Haidomyrmecinae, preserved as a rock impression in limestone of the Crato Konservat-Lagerstätte in northeastern Brazil. This finding also represents the earliest undisputed ant known to science.’

‘The distribution of known clades indicates that hell ants were widely distributed, with repeated interchanges between Cretaceous landmasses. Notably, northeastern Brazil’s paleoenvironment contrasts with other known deposits for Haidomyrmecinae, suggesting ecological diversity among these ants.’

Diagnosis:
‘The new genus can be confidently placed in Formicoidea by the possession of a prognathous head (Figure 1); elongated scape, which is nearly as long as the remainder of the antenna (Figure 2A); small meso- and metacoxal cavities (Figure 3E, right arrowheads); base of protrochanter strongly constricted, curved, and partially concealed by disticoxa (Figure 3E, left arrowhead); radial cell not produced distally (Figure 2C, left arrowhead); well-developed subpetiolar process (Figure 3F); petiole constricted posteriorly (Figure 2F); and second metasomal segment constricted on articulation with the third one (Figure 2G). Vulcanidris gen. nov. is placed among the Haidomyrmecinae based on the presence of a facial projection coupled with mandibles that articulate ventrally on the head (Figures 3B–3D). The new genus closely resembles Aquilomyrmex7 but can be differentiated by the presence of a slight constriction on the clypeal projection at level of antennal insertions (Figure 2E, lower arrowhead); forewing with three submarginal cells, vein 3r-m tubular (Figure 2C, right arrowhead); and body relatively less slender than Aquilomyrmex. Tomography reconstructions also indicate the presence of a tooth on the inner margin of the mandibles (Figures 3B and 3D), which could not be fully confirmed due to preservation. Finally, Vulcanidris gen. nov. can be differentiated from Cariridris33 by the head expanded laterally, smaller compound eyes, and larger body size.’

‘Head with compound eyes positioned anteriorly; elongated posterad, expanded laterally beyond the lateral level of the compound eyes; clypeal projection relatively long, extending anteriorly from between the compound eyes; ventral surface laterally with short, stiff setae (Figure 2E, upper arrowhead); antennae inserted anterior to the compound eyes; scape elongated; legs with femora swollen proximally, tapering progressively distally, and expanded at the articulations with the tibiae; forewing with strongly curved 2Rs (Figure 2D); large size, only known alate female measuring approximately 13.5 mm in length.’

‘The placement of both genera among Haidomyrmecinae is supported by the anteriorly directed mandibles that apparently articulate ventrally with the head, a feature unusual for insects,4,25 only found on rare occasions among extant groups.39 Another character shared with other Haidomyrmecinae is the clypeal projection, which is bordered laterally by stiff, short setae (Figure 2E). Nevertheless, the relatively complex wing venation (Figures 2C and 2D) indicates that the new species exhibits ant and wasp traits, reaffirming its position among stem-ant lineages.’

Results:
‘This is the first documentation of a hell ant recorded as a rock fossil, providing a unique opportunity to study the preservation of their unusual morphology in this medium. Cephalic adaptations of hell ants played a crucial role in their hunting and feeding habits, rendering the lineage as a major component of mid to late Cretaceous faunas.4,9,42 Micro-computed tomography of Vulcanidris cratensis sp. nov. revealed remarkable mandibles with dorsally directed tips contacting the clypeus to form an intervening cavity, likely used to seize the prey. The mandibular foramina are close to each other, receiving the proximally constricted mandibles, even resembling antennal sockets. This conformation suggests a higher capacity of mandible motion, a trait evolved by ants through different mechanisms.43 From this viewpoint, we can infer that their presumed specific predatory behaviors were already established by the Lower Cretaceous.’

‘The origin of ants likely occurred between the Late Jurassic and the Early Cretaceous,12,44 and Haidomyrecinae have been suggested as the earliest-diverging ant lineage.4,27 Given the available fossil data, hell ants seem to represent the oldest known major group of ants to diversify and spread across the globe. Morphological clock estimates suggest that the first split within Haidomyrmecinae occurred around 139.7 mya (95% HPD between 149.7 and 128.6 mya). Recent paleontological findings, coupled with phylogenomic molecular dating, have illuminated the faunal turnover affecting ants toward the end of the Cretaceous period.21,27,45 However, far less is known about the stem lineages from the Early Cretaceous. The discovery of Vulcanidris cratensis sp. nov. allows us to bridge the gap between ants and their wasp ancestors, pushing the earliest direct evidence of ants on Earth back to 113 mya, predating the fossil Formicidae from deposits in France and Myanmar by over 13 million years and aiding in calibrating the ant tree of life.’

‘In the present contribution, we report the oldest Haidomyrmecinae known to science, preserved as a rock impression in the limestone of the Crato Konservat-Lagerstätte in northeastern Brazil (Figure 1). The Crato Formation, part of the Santana Group in the Araripe Basin, is generally regarded as dating to the late Aptian stage of the Lower Cretaceous.32 Interestingly, another fossil from the same locality, Cariridris bipetiolata, has been considered as the earliest record of ants.33 However, the holotype remained inaccessible for decades, thus hindering the possibility of its re-examination and even casting doubt on its classification as an ant.34,35 The clarification on the identity of C. bipetiolata requires new evidence and analytical techniques and is beyond the scope of the present study. The present finding confirms the presence of ants in the Crato Formation, establishing the earliest record of ants known to science.'


Figure 1: Habitus of Vulcanidris cratensis gen. et sp. nov.
Figure 2: Photographs depicting details of Vulcanidris cratensis gen. et sp. nov.
Figure 3: Micro-CT reconstruction of Vulcanidris cratensis gen. et sp. nov.
Figure 4: Evolutionary history of Cretaceous ants


Sources:
Lepeco, A., Meira, O. M., Matielo, D. M., Brandão, C. R. F., & Camacho, G. P. (2025). A hell ant from the Lower Cretaceous of Brazil. Current Biology. doi.org/10.1016/j.cub.2025.03.023
‌
Ferrari, O. (2025, April 24). Researchers find oldest ant known to science—113-million-year-old “hell ant” with scythe jaws. Animals. www.nationalgeographic.com/animals/article/oldest-hell-ant-fossil-discovery